In addition to the standard framing square several other tools have been developed over the years to aid carpenters in framing and layout work although none has exhibited the simplicity and ease of use of the present invention. Among these prior art devices are those disclosed in U.S. Pat. Nos. 854,125, to Thompson; 991,693, to Brown; 1,641,168, to Jacques; 2,026,274, to Doyle; 2,028,052, to Easterly; and 3,456,353, to Iams. These devices are encumbered with many deficiencies such as moving parts which tend to collect dirt (Thompson, Easterly, and Iams), irregular and cumbersome shapes (Brown, Jacques, and Doyle), projections which limit the tool's usefullness (Brown and Jacques), and sharp edges which may harm the work (Brown).